Hippocampus

The hippocampus is a small, seahorse-shaped structure located deep in the brain’s medial temporal lobe. It is considered a part of the limbic system and plays a vital role in various cognitive functions, particularly in memory formation, learning, and spatial navigation.

Anatomy

The hippocampus is composed of two separate regions: the hippocampus proper (also known as Ammon’s horn) and the dentate gyrus. It is primarily divided into four subfields:

  1. CA1 (Cornu Ammonis 1)
  2. CA2 (Cornu Ammonis 2)
  3. CA3 (Cornu Ammonis 3)
  4. CA4 (Cornu Ammonis 4)

These subfields differ in terms of their cellular composition and connectivity patterns.

Function

The hippocampus is crucial for the consolidation of short-term memories into long-term memories, a process called memory encoding. It acts as a gateway for sensory information to enter the brain’s long-term storage systems. Additionally, it is involved in the spatial memory and navigation, enabling individuals to remember and navigate through their environment.

Studies have also linked the hippocampus to emotion regulation and the formation of episodic memories, which are a person’s unique autobiographical memories.

Role in Pathology

Damage or dysfunction in the hippocampus can lead to various cognitive impairments such as amnesia, difficulty in forming new memories, and spatial disorientation. It has also been implicated in neurodegenerative diseases like Alzheimer’s disease, where hippocampal atrophy is commonly observed.